Just south of Mars’ equator, abutting the Red Planet’s crater-studded highlands and smooth rolling lowlands, lies a broad plain wider than Texas, likely carved by a colossal impact more than 3.9 billion years ago. The blasted terrain of Isidis Planitia, a vast landscape of pitted ridges, light-colored ripples, and low dunes, today provides a forever home and tomb for one of Mars’ unluckiest robotic visitors.
This would-be martian invader made landfall 20 Christmases ago, never to be heard from again. Dead virtually on arrival on the planet and today dust-streaked and partly buried in the abrasive sand, Britain’s ill-fated Beagle 2 is now faintly visible to only our most advanced optics as a bright smudge amid an endless sea of wind-whipped ochre dust. It furnishes a stark reminder of the challenges of landing on this unforgiving world next door.
The fate of Beagle 2, which initiated its descent to the surface early on Christmas Day 2003 seemingly in good health before vanishing like a blip from a radar screen, proved a thornily intractable mystery for more than a decade. Its intended touchdown spot near the eastern edge of the 930-mile-wide (1,500 kilometers) Isidis Planitia would be repeatedly scoured by numerous orbiting spacecraft for clues. But Beagle 2’s smallness – just 6.5 feet (1.9 meters) across when fully deployed – put its detection just beyond the limits of available optics – truly an earthly needle in a martian haystack.
Many believed the 73-pound (33.2 kilograms) lander would never again be seen by human eyes, another woeful addition to a growing corpus of failed attempts to reach a world that might long ago have harbored large bodies of water, life-bearing minerals, and perhaps even the murmurings of primeval life itself.
Beagle 2 was named for another notable vessel
Its loss was a pity, for Beagle 2 – named for HMS Beagle, the Royal Navy brig-sloop that in 1831-1836 carried British naturalist Charles Darwin on a round-the-world voyage to seek evidence for his origin of species – should have spent up to six months on Mars, scooping soils and analyzing them for chemical signatures of ancient life. Its 43-inch-long (109-centimeters) robot arm housed stereoscopic cameras, a microscope, a pair of spectrometers, a versatile sampling drill, and a burrowing “mole.”
Beagle 2 hitched its 240-million-mile (400 million km) ride to the Red Planet aboard Mars Express, a boxy, 1-ton spacecraft bristling with eight scientific instruments to map Mars at resolutions finer than 33 feet (10 m), spectroscopically survey mineral concentrations, and scrutinise the thin, carbon-dioxide-rich atmosphere and its interactions with the interplanetary medium. Two radar antennas, each 60 feet (20 m) long, facilitated the sounding of Mars’ surface to a depth of 1.6 miles (2 km).
This powerful toolkit underpinned a fundamental scientific goal of Mars Express that could be summed in one word – water: whether it existed in the red planet’s more benign, habitable past, where it went and if it harbored life.
Mars Express was Europe’s first independent foray to the Red Planet. After the Russian/European Mars 96’s Proton-K rocket failed during ascent in November 1996, the European Space Agency (ESA) decided to stage its own mission. A tempting launch window in May/June 2003 fell when Earth and Mars were closest in their respective orbits – only 34.8 million miles (56 million km) apart – but engineers were challenged by a tight timeframe to develop, build, test, and launch it.
Costs and time were saved by reusing existing or off-the-shelf hardware, handing full responsibility to prime contractor Matra-Marconi Space and implementing new program-management strategies. At 150 million euros ($175 million USD in 1999, or $316 million today), it was the cheapest-ever Mars mission. And the name Express carried dual meanings, underscoring both a rapid concept-to-launch architecture and an exceptionally short cruise time to Mars, lasting just six months.
Delayed by a faulty electronics module, Mars Express took flight atop a Soyuz-Fregat rocket from Russia’s Baikonur Cosmodrome in Kazakhstan at 11:45 p.m. local time on June 2, 2003. After a half-year cruise through the inner Solar System, Beagle 2 was jettisoned on Dec. 19 and after five days of ballistic flight plunged into Mars’ atmosphere. Guarded from extreme deceleration temperatures by a hardy heat shield, a pair of parachutes and three airbags would carry the lander to a soft touchdown early Christmas morning.
But Europe’s visit from Santa never came. Efforts to call the lander – by NASA’s Mars Odyssey and ground-based observatories including the U.K.’s Jodrell Bank – proved fruitless, and when Mars Express overflew the intended landing site early in January 2004, its attempt to facilitate contact via ultra-high frequency communication also came to nothing. Beagle 2, it seemed, had vanished without a trace.
The Beagle 2 is declared lost in space
A month later, it was officially declared lost. And in May 2004, a UK/ESA inquiry found no single technical cause or fault, but pinpointed programmatic and organizational issues that increased a risk of failure.
Still, the search for the hapless lander continued, its inexplicable disappearance a mystery. Imagery from NASA’s Mars Global Surveyor in 2005 revealed an unfamiliar black spot, briefly elevating hopes that it could be Beagle 2. But optical analysis concluded it was an eroded crater.
Finally, January 2015 observations by the High Resolution Imaging Science Experiment (or HiRISE) on NASA’s 2006-launched Mars Reconnaissance Orbiter found a curious feature quite unlike any of the rocks or soils around it. Multiple images revealed several objects at locations where Beagle 2’s heat shield and parachute ought to have landed. Their shapes, structures, and the shadows they cast proved consistent with the bowl-shaped lander.
It was a remarkable achievement. With Beagle 2 found, it became apparent that the lander had reached the ground in one piece, tantalisingly close to its targeted spot. But it seemed that at most only two or three of its four petal-like solar arrays had unfurled, blocking its radio antenna and preventing it from communicating its status or transmitting any data.
This triumph of a successful landing was tempered by disappointment for a mission which came so close to success. There was also profound sadness, for Beagle 2 principal investigator Colin Pillinger of the U.K.’s Open University had died only a few months earlier in May 2014; he went to his grave never knowing that the fruit of his labors had, against so many odds, made it safely to Mars’ surface.
The impact of the Mars Express
Pillinger did, however, live to see some of achievements of Mars Express, which is today the second-longest-lived orbiter of the Red Planet, its two decades of continuous service surpassed only by NASA’s 2001-launched Mars Odyssey. From its elongated polar orbit, it has confirmed the presence of methane in the planet’s atmosphere, discovered the global extent of martian aurorae and pinpointed high-altitude clouds residing 50-60 miles (80-100 km) above the surface.
It offered tantalizing hints that ancient water once flowed here: from traces of flooding at Mangala Vallis to a frozen sea in the equatorial Elysium Planitia, from water-ice patches at extreme northerly latitudes in Vestitas Borealis to sulphate deposits in Juventae Chasma and from possible river channels in Nepenthes Mensae and Reull Vallis to hydrated silicates in Mars’ northern highlands. In 2019, it provided evidence of an interconnected underground network of lakes, five of which contained minerals necessary for life.
Mars Express data revealed that solar wind erosion may have contributed to the gradual disappearance of the thin atmosphere. And in 2007, it watched as fearsome dust storms ravaged the planet, temporarily raising global temperatures by 68-86 degrees Fahrenheit (20-30 degrees Celsius). It uncovered curious windblown sand features called yardangs, escarpments, and landslides, and it helped to date major Martian volcanic and tectonic events into five discrete epochs spanning timescales from 3.8 billion to 100 million years ago. The orbiter also completed multiple close flybys of Phobos, revealing Mars’ largest moon to be a battered rubble pile of aggregate debris with a porosity of 25-35%.
As if to make amends for the loss of Beagle 2, the hardy little spacecraft also supported other landings, helping to guide NASA’s Phoenix lander and Curiosity rover to smooth, on-point touchdowns in 2008 and 2012. Its visual monitoring camera, originally an engineering tool to monitor Beagle 2, was repurposed in 2008 as a Mars webcam for public outreach. And with its mission of exploration having surpassed 20,000 orbits of Mars and operations extended until the end of 2026, it surely has much more to contribute.